The vulnerability of adolescents with insulin-dependent diabetes mellitus (IDDM) to medical and psychosocial problems has been consistently documented. Moreover, there is convincing evidence that current clinical and educational approaches have not resulted in any effective strategies for preventing the predictable metabolic deterioration and psychosocial problems of many adolescent patients. In preliminary work, we have demonstrated that involving parents in an adolescent peer group intervention significantly reduced the frequency of hospitalizations and emergency room visits due to clinical deterioration (serious high and low blood glucose levels). Building on this promising approach, the research plan proposed here is also based on two recent major developments. First, new theories derived from developmental psychology have been proposed that emphasize both a new conceptualization of adolescent autonomy based on models of self-regulation as opposed to freedom from parents. Moreover, these theories have stimulated evidence documenting that interdependence between adolescent and parent, and not adolescent independence with detachment from parents, enhances adolescents' ego development, school functioning, and a spectrum of other psychosocial outcomes. The second development on which the proposed research is based is the growing consensus among empirical studies in psychosocial research in diabetes that adolescents given greater independence with diabetes management tasks have more mistakes in their self-care, are less adherent, and are in poorer metabolic control than those whose parents are more involved. The overall aim of this research is to study the impact of a 12-month outpatient Family/Responsibility intervention on medical and psychosocial outcomes in young adolescent patients with IDDM. This study is designed.to assess whether the Family/Responsibility Intervention is superior to simple attention alone (Attention Control condition), or to routine follow-up medical care (Standard Care condition) for adolescents with IDDM with respect to: (1) preventing the expected deterioration in metabolic control during early adolescence; (2) reducing rates of clinical deterioration (diabetes-related hospitalizations and school absences); (3) reducing the degree of diabetes-related conflict in the family; and (4) increasing adolescent adjustment to diabetes. In addition, we will explore the predictive relationships between indices of parent-adolescent interdependence, adolescent behavior problems, and family functioning to diabetes-specific medical and psychosocial outcomes of young adolescent patients. No intervention to date has been demonstrated to be acceptable, economical, and effective in preventing metabolic deterioration over the adolescent years. To address' this need, the proposed research will determine the effectiveness of the Family/Responsibility Intervention with medical and psychosocial outcomes of young adolescents with IDDM.